Lactation and especially milk, which is the product of that unique mammalian process, are routinely encountered within our daily lives. Nevertheless, they often are poorly understood by many, even including many who are engaged in the business of producing milk. The overall course goal is to introduce fundamental concepts that form the basis for understanding the biology of lactation, the biology of the mammary gland, and the products of that important physiological process.
As a learner in this course, you will be provided with a series of easily understood presentations that collectively will help you build a foundation for greater understanding of lactation. You will be able to engage with other learners so that you can extend your learning beyond the video presentations. Ultimately, you will be able to construct your own mental model for understanding the wide range of topics that relate to the biology of lactation. Upon completion of the course, you will be prepared to expand your knowledge and understanding of lactation from other sources and experiences as you pursue your individual interests.
Before you start the course, I suggest that you identify a question or several questions about lactation that you already have on your mind. This could be from your own experiences, something you read about or saw, or something you have wondered about. Write down your question(s) and use that to help you decide how to engage with the content of this course. You might engage with the modules in the order they are presented, or start with a module that is of particular interest to you, or pick and choose modules in any order. I encourage you to engage in all of the types of learning activities that this course has to offer, including but not limited to, the discussion forums, quizzes, peer-review assignments, and concept maps and other learning aids.

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Module 4: Mammary Gland Development

The tissue that we know of as the mammary gland (or udder or breast) may appear as relatively uncomplicated compared with some internal organs such as the heart or brain. The gland is outside the body wall, has a nipple or teat in most species, and has a series of ducts by which milk that is produced in microscopic blind tubes can be expressed from the gland. How can such a gland develop and what regulates that development? It turns out that the initial stage of development occurs extremely early in the fetal development of the animal. It then proceeds through a series of developmental phases, many of which are closely linked with the reproductive functioning of the animal, and eventually leading to the time when the gland is producing milk. Furthermore, the mammary gland is one of a few tissues that undergoes repeated cycles of development, functioning, regression, and redevelopment, again associated with the reproductive cycles of the animal. This module describes the various stages of mammary development and provides the framework for understanding how these stages relate to each other, as well as to the functionality of the gland.